How Does the Microbiome Change in Eczema?

Our skin is covered in bacteria - learn how bacteria is important in eczema

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Billions of bacteria live on the skin in a community known as the microbiota. The microbiota is critical in maintaining overall health, as well as the health of our skin, especially when it comes to atopic dermatitis (eczema). Atopic dermatitis (eczema) is a chronic rash that involves dryness, redness, intense skin itching, and an increased risk for skin infections.

The Skin’s Microbiota Shifts in Active Eczema

The microbiota of the skin is normally a diverse community of bacteria. The more diverse, the better.[1] However, in eczema there is a shift in the community so that one of the bacteria, Staphylococcus aureus (S. aureus), becomes dominant.[2] When S. aureus overgrows to become dominant, the overall skin microbiota becomes less diverse (Table 1). Researchers have found that the skin microbiota shifts toward S. aureus before the eczema flare becomes visible on the skin.[2]

Table 1. Microbiome in Eczema

State of the Skin

Diversity of the Bacteria

Inflammation

Eczema is controlled

High

(Diverse)

Low

Eczema is active

Low

(Dominant for S. aureus)

High

Active eczema is restored to a controlled state

High

(Diverse)

Low

The Staphylococcus family of bacteria is made up of several different species. Although not all of them are bad for the skin, S. aureus is associated with flares of eczema.[2] Other common species include S. epidermidis, S. cohnii, and S. capitis. These species are thought to have a beneficial effect in keeping the skin’s microbiome more diverse and reducing inflammation. One study showed that infants that were colonized with the S. epidermidis and S. cohnii commensals by 2 months of life had a reduced risk to develop eczema by 1 year of life.[3] Other studies have shown that when active eczema comes back into control with treatment, the microbiome shifts to having more of the “good” Staphylococcus species of bacteria with greater overall diversity.[2]

Restoring the Microbiota in Eczema

Researchers are looking for ways to restore a healthier microbiota in those with eczema. There are two main approaches: 1) The first approach is to try to prevent the microbiota from shifting to an unhealthy state. 2) The second approach is to be reactive to changes that have already occurred. Medications like antibiotics are helpful when there are signs of infection (such as redness, honey crusting, pus, and fever).

Preventative approaches

Bleach baths: Dilute bleach baths are similar to taking a swim in a swimming pool. Dilute bleach is not irritating to the skin and can help improve eczema. Learn more about bleach baths and how to choose bleach.

Use antibiotic ointment in the nose: Our noses serve as a source of bacteria for the rest of the body. Researchers have shown that eczema could be improved by using bleach baths along with treatment of the nose with mupirocin (an antibiotic) to reduce aureus.[4]

Regular moisturizer use: Moisturizers help keep the skin in a protected state. One study showed that regular moisturizer use helped to keep the microbiome diversified.[5]

A varied, well- balanced diet: Eating a wide variety of fruits and vegetables, as well as high fiber grains, helps to diversify your microbiota.[6,7]

Reactive approaches

Antibiotics: In some cases, the skin can become very red (suggesting that the microbiome has shifted to one dominant bacteria that is causing inflammation) or can result in infection. In both cases, antibiotics can help restore balance to the skin. If there is fever or pus draining from the skin, a physician needs to immediately evaluate the skin.

Steroids: Steroids have an important role in reducing inflammation and are very effective in treating eczema that has flared. The use of steroids to reduce inflammation is associated with reducing the dominance of aureus.[2,8] The goal with steroids is to use them for a short time to reduce flares and then transition to non-steroid based therapies for maintenance.

The Role of Probiotics

Oral probiotics seem to have a beneficial role for eczema.[9] However, there are still many questions as to how probiotics work. They appear to modify how the immune system works,[9] but it is unclear how they may change the skin microbiome. A number of questions still remain, including the following:

Which bacteria work best for eczema?

What is the best dose for taking probiotics?

Does the probiotic create long-term change in the gut or the skin or are the changes temporary?

How does the microbiome in the gut change in those with eczema?

Conclusions

The microbiome plays an important role in skin health. It appears that as the microbiome becomes more diverse, the skin is in a healthier state. In eczema, a dominance of the bacterium S. aureus is associated with more inflammation. As research continues to build our knowledge in this area, we hope to understand more about how the gut’s microbiome connects to the skin in eczema, how probiotics may be used effectively, and what strategies can be used to keep the skin microbiome in a healthier state.

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